Proceedings of the 30th International Workshop on Description Logics, Montpellier, France, July 18-21, 2017.
The International Workshop on Description Logics is the main annual event of the Description Logic research community. It is the forum at which those interested in description logics, from both academia and industry, meet to discuss ideas, share information, and compare experiences. The workshop explicitly welcomes submissions from researchers that are new to the area and provides quality feedback via peer-reviewing, while at the same time being of an inclusive nature with a very high acceptance rate. There are only informal (electronic) proceedings and inclusion of a paper there is not supposed to preclude its publication at conferences. Further information can be found on the DL Web pages at http://dl.kr.org/.
Our concern is answering ontology-mediated queries (Ο q), whereΟ is a set of linear tgds and q a conjunctive query (CQ) of bounded hypertree width. Assuming that the arity of predicates is bounded, we show that polynomial-size nonrecursive Datalog rewritings can be constructed and executed in (i) LOGCFL for OMQs with ontologies of bounded existential depth; (ii) NL for OMQs with ontologies of bounded depth and CQs whose hypertree decompositions have a bounded number of leaves; (iii) LOGCFL for OMQs with acyclic CQs whose join trees have a bounded number of leaves.